As display devices which are a kind of semiconductor devices and are usable for electric appliances and electronic devices, a liquid crystal display device using an electro-optical effect of a liquid crystal material and an organic EL (electroluminescence) display device including an organic electroluminescence (EL) element have been developed.
Especially, a display device including an organic EL element used as a display element has a large viewing angle, provides high definition display, and is allowed to be formed on a flexible substrate. Japanese Laid-Open Patent Publication No. 2013-015835 discloses a display device including an organic EL element provided on a flexible substrate.